As long as the size difference is not too big it should work well (ie. adult 12" senegal and a 1" baby raphael). They will most likely completely ignore each other. I've heard raphaels like to hide, and they hide well.
The Raphael will be fine they are very hard much like a pleco I have a 4"+ one in my cichlid tank w/ no problems. Twig cats however are very skittish community fish.
I have two raphaels: one stripped and one spotted and they did fine with my two birchirs in the big tank but they were both 3" long. now my stripped raphael is almost 4" long. and yes they are spiny.